Before Mr Trump took office, there were 654 miles of barrier along the southern border - made up of 354 miles of barriers to stop pedestrians and 300 miles of anti-vehicle fencing.

Trump wants a 2,000 mile wall.

Estimated Cost for Trump's Wall

The Department of Homeland Security (DHS) previously estimated a wall spanning half the border would cost up to $25 billion, but it has now said it is still looking at options to determine the price tag.

US Customs and Border Protection (CPB) says that, on average, it costs approximately $6.5 million per mile to construct a new border wall or replace existing legacy fence.